The BEST would be a Perazzi 20 ga. skeet gun. That is the best shotgun out there but expect to pay the best shotgun price to go along with that. I think 99% of the shotguns on the lines at the Olympcs this year were Perazzi.

Though in he real world I would get her a Remington 1100 or 1187 in 20ga. the gas operated semi-auto like the 1100 is soft of the shoulder and not so hard on the pocket book as the first one I mentioned (which by the way comes in at about $10,000 ea). Take a look at the Stoeger M2000 it is a Benelli on the inside. You tell me which is which in the pictures below. One is a Stoeger one is a Benelli.

As a short woman who shoots trap/skeet/sporting clays, I love the over unders & side by sides.

I have a winchester 23 with 28 barrels, and a Browning WSSF which was made for women. The downside is that Browning discontinued the line. (personally, if they did not make the majority of them TEAL colored, they would have sold more ).

my 12 ga remington 1100 shoots super-soft recoil, so I would imagine a remington 20 ga would be even softer. The first thing you need to do, is let her shoot a few rounds from a gun that really kicks, then immediately let her shoot her softer-recoil shotgun. She'll notice how much softer it is, and not ever complain.

Can't beat a Remington 1100 LT20 youth model or a regular model with a youth stock. Soft recoiling, dependable, excellent pointing, and later if she decides she wants a Kreighoff, you should have no trouble selling it. I've started 5 different people out shotgun shooting with one of these with very good results.